Submitted to: American Forage and Grassland Council Conference Proceedings
Publication Type: Proceedings
Publication Acceptance Date: 4/13/1997
Publication Date: N/A
Interpretive Summary: When plants are exposed to bright sunlight and low temperatures, the oxygen in the atmosphere can become toxic. Plants have a number of chemicals that serve to detoxify the oxygen compounds and thereby prevent damage. Dried seaweed when powdered and dissolved in water has been shown to improve the ability of plants to withstand some types of environmental stress. In this study the effect of seaweed on oxygen detoxification was studied in the forage grass Tall Fescue. Seaweed extract was found to increase the levels of several enzymes involved in oxygen detoxification; superoxide dismutase, gluthathione reductase and ascorbate peroxidase. In spite of these increases the growth of the plants was reduced as a result of the environmental stresses experienced by the plant. While plant stress was not completely alleviated by seaweed extract, the ability to increase oxygen detoxification with the application of seaweed, a natural product, holds promise for reducing the adverse effects of environmental stress in tall fescue.
Technical Abstract: Plant cells are protected against oxidative damage by antioxidant systems that involve several enzymes including superoxide dismutase (SOD), glutathione reductase (GR), and ascorbate peroxidase (APX). Genetically similar endophyte-infected (E+;100% ) and endophyte-free (E-;0%) 'Ky-31' tall fescue was grown in replicated field plots near Lubbock, TX. Plots were treated with 0 or 3lb seaweed (Ascophyllum nodosum) extract/acre and irrigated with water to provide 100%, 50%, or 0% replacement of potential evapotranspiration (PET) over rainfall (18in./yr average). Seaweed extract generally increased activities of SOD, GR, and APX in tall fescue. At 100% PET, seaweed increased (p<.01)SOD, but the response was greatest in E+ tall fescue (interaction P<.05). More SOD was present in E+ than E- tall fescue (P<.001). Under rain fed conditions, no effect of endophyte was present on SOD or APX, but GR was higher (P<.05) in E+ than in E-tall fescue. Seaweed dextract increased (P<.05) total seasonal yield of E- tall fescue when 100% of the PET was replaced, but yield tended to be lower (P<.09) in seaweed treated E- tall fescue under 50% PET or rain-fed conditions. Seaweed extract had no effect on total seasonal yield of E+ tall fescue, but the numeric values were inverse to those observed with E- tall fescue.